Returns 'INT NOT NULL' -- relying on the sequence autocreated by 'SERIAL' can get you into trouble since long table names get truncated. Just create your own sequence and specify it in the 'sequence_name' key of your object config (see SPOPS::DBI::Pg).

Since PostgreSQL supports a sequence-based increment type, think about adding a hook for an extra statement to be registered and modifying '%%INCREMENT%%' to be 'INT NOT NULL' and the extra statement to create a sequence of a given name.